Pump control



Sept. 19, 1961 R. M. TUCK 3,000,319

PUMP CONTROL Filed Aug. 7, 1957 97 INVENTOR.

foaifWZi ATTORNEY United States Patent 3,000,319 PUMP CONTROL Robert M. Tuck, Indianapolis, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Aug. 7, 1957, Ser. No. 676,744 3 Claims. (Cl. 103-40) This invention relates to a multi-piston pump and more particularly concerns a radial piston pump incorporating means whereby at a predetermined discharge pressure one or more of the pumping cylinders is cut out or inactivated.

The invention has as its principal object to provide means for the purpose indicated characterized in operation in that a further increase in discharge pressure, with one of the cylinders already inactivated, is marked by the cutting out of one or more additional cylinders, the exact number depending on the magnitude of the increased pressure.

Another object of the invention is to provide such means which under a condition of decreasing discharge pressure operates similarly but oppositely, i.e., on a further decrease in the discharge pressure, with a previously inactivated cylinder restored to operation, an additional number of inactivated cylinders are successively restored to operation as determined by the extent of the further decrease in the discharge pressure.

An additional object is to provide means as described adapted for actuation by fluid pressure.

Still other objects and features of the invention will become apparent from the following description of a preferred embodiment thereof. The description will proceed with the aid of the accompanying drawing wherein some of the parts appear in section and some are shown in elevation.

As will be seen from the drawing, the pump casing or housing is comprised of cover members and 12, these being secured by bolts 14 to intermediate members 13 and 15, respectively. The pump is driven by a shaft 16 splined at 18 and having a cam enlargement 20. Within the pump housing, the shaft turns in roller bearings 22 of any suitable design.

Housing member 13 is formed to provide a plurality of cylinders 19 adapted to accommodate pistons 24, each of which is connected via retainer rings 26, interconnected by pins 28, to a race member 30 spaced from the cam portion 20 of the drive shaft 16 by roller bearings 32. As shown, these roller bearings are kept confined between the cam portion of the shaft and the race by the retainers 26.

With the arrangement as shown and described, it should be clear that rotation of the drive shaft 16 is marked by reciprocation of the pistons 24 in the corresponding cylinders 19.

Cover member 12 will be seen formed to provide an inlet cavity 34. Between such cavity and each cylinder 19 is a check valve 36 which opens on the suction stroke of the piston. For the discharge valving there is provided a flexible band 40 encircling the cylinder bank with a slight clearance. In operation, such band is held tightly against the outer ends of the intaking cylinders by the pressure of the fluid passing from the discharging cylinders, such action proceeding with rotary movement of the band which is consequently largely self-cleaning.

Outward of the band 40 is an annular discharge chamber 42 common to all of the cylinders and communicating with the discharge port 44.

For the purposes of the present invention, the pump incorporates a valve, generally denoted by the numeral 50, comprising a housing portion 52 and a plunger 54, the latter being loaded by a spring 56. The plunger 54 3,000,319 Patented Sept..19,.

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includes a pair of lands 58, 60 interconnected via astem portion 62.

The housing 52 of valve 50 will be noted as provided with three annular channels 64, 66, 68. Channel 66 communicates with the discharge chamber 42 via a passage 70, which channels 64 and 68 communicate via passagw 71 and 73 with chambers 72 and 74, respectively, at the opposite ends of a cut-out piston 76. Such piston has an integral flange 78 provided with a series of pins 80, the number of pins conforming with the number of pumping cylinders. These pins vary in length in a stepwise fashion and each is disposed in juxtaposition to one of the check valves 36.

A passage 77 communicating with the chamber housing the spring 56 and the bore of the valve housing'52 simply a bleed passage.

To describe the operation of the pump, let it be taken that the same has been operating normally with all of the pumping cylinders working. Assuming now lessening of the demand on the pump, the pressure in the discharge chamber 42 will, of course, increase. When such pressure has attained a predetermined value, plunger 54 or valve 50 will be forced leftward against the resistance of spring 56 to interconnect passages 70 and 71, with the result that the developing pressure in chamber 72 will force the cut-out piston 76 leftward. This action is accompanied by engagement of the longest pin 80 with the corresponding check valve 36 so that the corresponding cylinder 19 becomes open to the intake cavity 34. Thus, on the discharge stroke of the particular piston, the fluid which was withdrawn from the cavity on the suction stroke of the piston is returned thereto instead of being forced past the band 40 into the discharge chamber 42. In the event of a further increase in the discharge pressure, cut-out piston 76 will be forced further leftward, since the increased pressure is reflected in the chamber 72,, to open up an additional number of the check valves 36 as necessary to maintain the pump discharging pressure constant.

When demand is once again made on the pump, the resulting decrease in the discharge pressure, reflected between the lands 58 and 60 of valve 50, allows spring 56 to shift the plunger 54 rightward to its shown position causing rightward movement of the cut-out piston 76 by reason of passage 73 and progressive restoration of the pumping cylinders to operation.

What I claim is:

1. In a pump including a housing confining a plurality of radially arranged cylinders and a corresponding number of pistons in said cylinders, said housing having therein an inlet cavity communicating with said cylinders via circumferentially arranged individual inlet passages, each of said passages having a check valve therein normally closing the passage during the discharge stroke of the piston in the corresponding cylinder, the combination of an axially displaceable piston having flange carrying pins of varying length adapted to engage said check valves, said piston being responsive to and actuated by the pressure of the discharge fluid, movement thereof being accompanied by sequential opening of said valves.

2. In a pump including a housing confining a plurality of radially arranged cylinders and a corresponding number of pistons in said cylinders, said housing having therein an inlet cavity communicating with said cylinders via circumferentially arranged individual inlet passages, each of said passages having a valve therein normally closing the passage during the discharge stroke of the piston in the corresponding cylinder, the combination of stepped means circumferentially arranged in correspondence with the arrangement of said passages and said valves and axially displaceable by fluid pressure, said means comprising two reaction surfaces each confined in a separate chamber in said housing, and control means in said housing whereby discharge fluid under a first predetermined pressure is admitted to one of said chambers to axially displace said stepped means toward said valves to open one or more of the same and whereby discharge fluid at a second predetermined pressure is admitted to the other of said chambers to axially displace said stepped means in the opposite direction.

3. The combination of claim 2 where said stepped means takes the form of a piston the ends of which provide the opposed reaction surfaces, said piston having a flange carrying pins adapted to engage said valves, said pins being of varying length to provide the stepping.

References Cited in the file of this patent UNITED STATES PATENTS 1,521,461 Madden Dec. 30, 1924 4 Redfield Feb. 8, 1927 Hilger Mar. 19, 1929 Brown Nov. 3, 1931 Mantle Mar. 3, 1942 Heitchue June 11, 1946 Staude a Feb. 5, 1952 Pauget Sept. 1, 1953 Mott Sept. 29, 1953 Ball Dec. 1, 1953 Torel1j -a Dec. 9, 1958 FOREIGN PATENTS Great Britain Sept. 7, 1949 France Feb. 16, 1937 Germany July 8, 1949 

